Genetic polymorphisms in the CCR5 locus impact susceptibility to HIV-1 infection and rates of disease progression. This project investigates the biologic basis for these impacts. Promoter polymorphisms have been shown to impact the rate of CCR5 receptor recycling, and may have the effect of reducing or increasing the number of available target cells for HIV-1 entry, a process that depends uupon CD4 and CCR5 expression. GCRC Normal Blood Donors are essential to this project.